Coverings for Viscoelastic Foam Mattresses

ABSTRACT

Covers for mattresses having a reclining surface of viscoelastic foam have a fabric body with a first surface disposed in engagement with the reclining surface; an opposite, second surface disposed for engagement by a person reclining upon the cover; and at least one air flow region defined by the fabric body for enhanced circulation of air between the reclining surface of viscoelastic foam and an opposed skin surface of the person reclining upon the cover.

TECHNICAL FIELD

This disclosure relates to viscoelastic foam mattresses and fabriccoverings for such mattresses.

BACKGROUND

A trend in the mattress market is the use of viscoelastic foams, alsoreferred to as “memory foams” or foams having compressible memory toform a sleeper-supporting surface. Viscoelastic foam conforms to theshape of an object resting upon its surface, and regains its generallyflat surface once the object is removed. These foams, described, forexample, in U.S. Pat. No. 6,734,220, the entire disclosure of which isincorporated by reference herein, are generally formed of curedpolyurethane-based viscoelastic polymer. Viscoelastic mattresses areoften covered with a fabric cover, typically made of a fabric referredto as “ticking.”

SUMMARY

In various aspects, the disclosure features covers for mattresses havinga reclining surface of viscoelastic foam.

In one aspect, the cover comprises a circular knit fabric body havingfour-way stretch and defining: (a) a first pile surface disposed inengagement with the reclining surface; (b) an opposite, second pilesurface disposed for engagement by a person reclining upon the coverwith the first surface disposed in engagement with the recliningsurface; and (c) at least one air flow region for enhanced circulationof air between the reclining surface of viscoelastic foam and an opposedskin surface of the person reclining upon the cover.

In some implementations, at least one of the first pile surface and thesecond pile surface defines one or more regions with relatively highpile disposed among one or more regions of relatively low pile or nopile, with the one or more regions of relatively low pile or no piledefining the one or more air flow regions for enhanced circulation ofair between the reclining surface of viscoelastic foam and an opposedskin surface of the person reclining upon the cover. Some of theseimplementations include one or more of the following features. The oneor more regions with relatively high pile and the one or more regions ofrelatively low pile or no pile are arranged upon at least one of thefirst pile surface and the second pile surface by engineered bodymapping techniques in a manner to position the one or more air flowregions for enhanced circulation of air between the reclining surface ofviscoelastic foam and an opposed skin surface of the person recliningupon the cover in accordance with requirements of corresponding bodyregions of the person reclining upon the cover. The one or more regionswith relatively high pile and the one or more regions of relatively lowpile or no pile are arranged upon at least one of the first pile surfaceand the second pile surface by standard knitting design techniques in amanner to position the one or more air flow regions for enhancedcirculation of air generally between the reclining surface ofviscoelastic foam and an opposed skin surface of the person recliningupon the cover in a regular pattern. Contrasting height among regions ofrelatively high pile and regions of relatively low pile or no pile isestablished by contrasting height of sinker loops. The sinker loops arein unnapped yarn form; in napped, velour form; or in cut loop formwithout pre-napping. The fabric body comprises a fabric laminate. Thefabric body comprises stretch stitch yarns, e.g., stitch yarns withspandex. The fabric body comprises hydrophilic fibers. The fabric bodycomprises fibers of synthetic material, e.g., selected from the groupconsisting of polyester, acrylic, nylon, these fibers renderedhydrophilic, and blends thereof. The fabric body comprises materialselected from the group consisting of cotton and wool. The fabric bodyhas chemical treatment for one or more properties selected from thegroup consisting of wicking enhancement, stain release, waterrepellency, stain repellency, antimicrobial properties, and oilrepellency. In some implementations, the fabric body comprises a doublebar raschel warp knit construction.

In some implementations, the one or more regions of relatively high pilecomprises a plurality of spaced-apart pile pillars and the one or moreregions of relatively low pile or no pile comprises intersectingchannels extending among the pile pillars and defining the one or moreair flow regions for enhanced circulation of air between the recliningsurface of viscoelastic foam and an opposed skin surface of the personreclining upon the cover. In some of these implementations, the fabricbody comprises a knit structure with about 16 to about 28 wales per inchand about 14 to about 36 courses per inch. The fabric body has finenessin a range of about 40 to about 600 denier, with individual fibershaving fineness in a range of about 1 dpf to about 12 dpf.

In another aspect, the cover comprises a fabric body defining (a) afirst surface disposed in engagement with the reclining surface; (b) anopposite, second surface disposed for engagement by a person recliningupon the cover; and (c) at least one air flow region for enhancedcirculation of air between the reclining surface of viscoelastic foamand an opposed skin surface of the person reclining upon the cover.

In some implementations, the fabric body comprises a first fabric layerdefining the first surface and a second fabric layer defining theopposite, second surface, with the one or more air flow regions definedtherebetween; and the fabric body further comprises a plurality ofintermediate members extending generally between the first fabric layerand the second fabric layer and through the one or more air flow regionsfor enhanced circulation of air between the reclining surface ofviscoelastic foam and an opposed skin surface of the person recliningupon the cover. Some of these implementations include one or more of thefollowing features. The plurality of intermediate members are disposedto resiliently urge apart the first fabric layer and the second fabriclayer. The first fabric layer is permeable to water vapor andimpermeable to liquid water. Each of the first fabric layer and thesecond fabric layer comprises stitch yarn. The stitch yarn of the firstfabric layer has fineness in a range of about 50 to about 600 denier.The stitch yarn of the first fabric layer has individual fiber finenessin the range of about 0.3 to about 6.0 dpf. The stitch yarn of the firstfabric layer comprises hydrophilic fibers. The stitch yarn of the firstfabric layer comprises a synthetic material, e.g., selected from thegroup consisting of polyester, acrylic, nylon, these fibers renderedhydrophilic, and blends thereof. The stitch yarn of the second fabriclayer comprises natural fibers. The stitch yarn of the second fabriclayer comprises material selected from the group consisting of cottonand wool. The second fabric layer further comprises lay-in yarn held bythe stitch yarn, e.g., an elastomeric yarn. The lay-in yarn comprisestotal fineness in a range of about 70 to about 300 denier.

The disclosure also features methods for forming a cover for a mattresshaving a reclining surface of viscoelastic foam.

For example, in one aspect, the disclosure features a method including(a) forming a circular knit fabric having four way stretch, with a firstpile surface and an opposite, second pile surface and defining at leastone air flow region for enhanced circulation of air between thereclining surface of viscoelastic foam and an opposed skin surface ofthe person reclining upon the cover; and (b) forming the circular knitfabric into a cover for a mattress having a reclining surface ofviscoelastic foam.

In a further aspect, the disclosure features covers for a mattresshaving a reclining surface of viscoelastic foam, the cover formed by theabove methods.

The term “pile,” as used herein, includes pile surfaces formed by anydesired method, including but not limited to cut loops, loops cut on theknitting machine, loops cut off the knitting machine, and raised fibers.

Some implementations exhibit one or more of the following advantages.The fabric cover conforms generally to the surface of the viscoelasticfoam mattress as the foam changes in configuration from its originalflat form to a conforming, compressed state and back to the originalflat form. The cover provides minimum restriction to movement of thefoam, so there is less tendency for the foam to bulge and/or crease. Thefabric cover is comfortable to the user. Preferred mattress coversdefine one or more regions of air circulation between the viscoelasticfoam surface of the mattress and the opposed skin surface of a personsleeping on the mattress, so that even as the viscoelastic foam conformsclosely to the shape of the person sleeping on the mattress, the coverpermits circulation of air between the surface of the mattress and theperson's skin, to allow the person to sleep comfortably, includingduring warmer conditions.

The details of one or more implementations are set forth in theaccompanying drawings and the description below. Other features andadvantages will be apparent from the description and drawings, and fromthe claims.

DESCRIPTION OF DRAWINGS

FIG. 1 is a side view of a mattress cover on a mattress having aviscoelastic foam surface layer, with a sleeping person reclining uponthe mattress surface.

FIG. 2 is a perspective view of a mattress cover according to oneimplementation, in which a raised upper surface and/or a raised lowersurface of the cover defines one or more air flow regions for enhancedcirculation of air between a sleeping person and the viscoelasticsurface of the mattress. FIG. 2A is a highly enlarged partialperspective view of area A-A in FIG. 2.

FIG. 3 is a sectional view of a mattress cover according to anotherimplementation, in which a raised upper surface and/or a raised lowersurface has one or more regions of relatively high pile among one ormore regions of relatively low or no pile, the regions of relatively lowor no pile defining one or more air flow regions for enhancedcirculation of air between a sleeping person and the viscoelasticsurface of the mattress. In this implementation, the regions arearranged according to engineered body mapping techniques to accommodatecorresponding body regions of a sleeping person.

FIG. 4 is a perspective view of a mattress cover according to anotherimplementation, similar to the implementation of FIG. 3, in which araised upper surface and/or a raised lower surface has one or moreregions of relatively high pile among regions of relatively low or nopile, the regions of relatively low or no pile defining air flow regionsfor enhanced circulation of air between a sleeping person and theviscoelastic surface of the mattress, the regions in this implementationbeing evenly spread in an overall pattern according to standard knittingdesign techniques.

FIG. 5 is a sectional view of a mattress cover according to anotherimplementation of the disclosure, in which pile pillars extending fromupper and/or lower surfaces of the cover define air flow regions forenhanced circulation of air between a sleeping person and theviscoelastic surface of the mattress.

FIG. 6 is a sectional view of a mattress cover according to a furtherimplementation of the disclosure, in which intermediate members span airflow regions defined between the upper surface and the lower surface ofthe mattress cover for enhanced circulation of air between a sleepingperson and the viscoelastic surface of the mattress.

FIG. 7 is a perspective view of a mattress cover in which the smooth,technical face surface of two fabric layers are adhered togetherface-to-face to form a two-layer laminate, with their respective outer,technical back surfaces facing outward.

FIG. 8 is a perspective view of the mattress cover of FIG. 3.

FIG. 9 is a perspective view of the mattress cover of FIG. 5.

FIG. 10 is a perspective view of the mattress cover of FIG. 6.

FIG. 11 is a side elevational view showing loop structure of atwo-layer, three dimensional fabric suitable for use in the mattresscover shown in FIGS. 6 and 10.

FIG. 12 is a side elevational view showing a larger area of the fabricof FIG. 11.

FIG. 13 is a perspective view of the fabric of FIG. 12 viewed from itstechnical back and illustrating formation of sinker loops.

FIG. 14 is a front elevational view of the fabric of FIG. 12 viewed fromits technical face.

FIG. 15 is a side view showing terry loops of the fabric construction ofFIG. 12 prior to (a) napping on the technical face and (b) shearing onthe technical back.

FIG. 16 is a side view of terry loops on the technical face of thefabric construction of FIG. 15 after napping.

FIG. 17 is a side view of terry loops on the technical back of thefabric construction of FIG. 16 after shearing.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

A mattress 100 having a viscoelastic foam surface layer 101 with a cover102 is shown diagrammatically in FIG. 1. The mattress cover 102 isformed of a knitted fabric having at least two-way stretch with goodrecovery, e.g., a circular knit or warp knit fabric. The fabrictypically includes spandex yarn, to allow the knitted fabric to conformto deformation of the compressed viscoelastic foam in multipledirections under load, and to avoid restricting recovery of theviscoelastic foam when the load is removed or reduced. Preferably thefabric has four-way balanced stretch, i.e., the elongation when thefabric is subjected to a load is substantially the same along the lengthand width of the fabric. The mattress cover is constructed to define oneor more air flow regions for enhanced circulation of air between thereclining surface of viscoelastic foam and skin surfaces of a personreclining upon the cover. The regions for enhanced circulation of airmay be provided in various forms.

Referring to FIG. 2, in one implementation the fabric 211 formingmattress cover 102 includes raised surfaces 105, 107 on its technicalface and technical back. As indicated by the arrow in FIG. 2A, theseraised surfaces, formed of pile or loops, allow air flow between thepile fibers or loops. Thus, the raised surfaces provide enhancedcirculation of air. Preferably, the fabric 211 is a circular knit fabrichaving four way stretch.

In another implementation, for example, as shown in FIGS. 3 and 8, thefabric 211′ forming mattress cover 102′″ has a raised surface with athree-dimensional geometry in which one or both surfaces define apredetermined pattern of regions of no loops or low loops or pile andregions of relatively higher loops or pile. The regions of relativelyhigher pile 110 are positioned and constructed to support the personreclining upon the cover and spaced from the reclining surface ofviscoelastic foam, with regions of low pile and no pile 112 defining airflow regions for enhanced circulation of air through the air flowregions, between the reclining surface, F, of viscoelastic foam and theskin surface, S, of the person reclining upon the cover 102′″. In somecases, the fabric 211′ is an engineered thermal fabric with regions ofcontrasting cushioning and air-flow capacity and performance, arrangedby body mapping concepts, tailored to the different requirements ofdifferent regions of the sleeper's body. Greater cushioning will beprovided by the regions 110 of relatively higher loops, reducingpressure on regions of the body that tend to compress the mattress more,e.g., hips and shoulders. Moreover, air ventilation will occur in the noloop or low loop regions 112 disposed among the regions 110 ofrelatively higher loops, thereby increasing the comfort level byreducing perspiration and heat build-up. Thus, such fabrics 211′ willtend to optimize the comfort level of the person while sleeping. Thedistribution of the low and high pile areas can be selected to suitparticular conditions and user preferences, and different products canbe provided having different distributions.

The high and low pile areas may be distributed in a regular pattern, forexample in bands, to simplify manufacture. For example, as shown in FIG.4, a lower band region 220 having relatively higher pile height and/orrelatively higher fiber density may be positioned to extend generallyacross the person's hips and an upper band region 222, also ofrelatively higher pile height and/or relatively higher fiber density,may be positioned to extend generally across the person's shoulders. Atthe upper and lower extremities, respectively, of the mattress cover, atop region 224 of relatively low pile or no pile is positioned to extendgenerally beneath the person's head and along the side wall at the headof the mattress and a bottom band region 226 of relatively low pile orno pile is positioned to extend along the side wall at the foot of themattress. An intermediate region 228, also of relatively low pile or nopile, is positioned to extend generally across the person's upper torso.

In another implementation, for example, as shown in FIGS. 5 and 9, afabric 111 forming a mattress cover 102″ has a raised surface on thetechnical back and a velour or terry sinker loop surface on thetechnical face. The raised surface on the technical back, disposed toface the viscoelastic foam surface layer 101, defines gaps or channels104 allowing movement of air along the surface of the fabric, e.g.,between the surface, F, of the mattress and the skin surface of theperson reclining on the mattress. The velour or terry loop on thetechnical face of the fabric disposed to face the skin, S, of thereclining person, similarly defines gaps or channels to allow aircirculation between the skin surface of the person's body and theviscoelastic surface of the mattress. The surface of raised pile fabric111 defines spaced-apart pile pillars 103 among intersecting channels104 defined therebetween. The pile pillars may be found at one surfaceof the fabric, or at both surfaces (technical face and technical back)of the fabric, e.g., as shown in FIGS. 5 and 9. The pile pillars defineair flow regions, allowing enhanced circulation of air between thereclining surface, F, of the viscoelastic foam and the skin surface, S,of a person reclining upon the cover 102″. The channels will alsoenhance moisture evaporation. The channels 104 may have any desiredconfiguration; for example the channels may be in discrete regions ofthe fabric which may be interconnected or not interconnected, or may becontinuous from one edge of the fabric to the opposite edge.

In another implementation, shown in FIGS. 6 and 10, a fabric body 11forming a mattress cover 102′ has the form of a two-layer, spacer fabrichaving an air circulation space defined between layers. For example, thefabric 11 may be a three-dimensional double knit fabric consisting of afirst layer 13 and a second layer 15 that are spaced apart resilientlyby interconnecting yarns 21. Such fabrics will be discussed in detailbelow. The resilient interconnecting yarns 21 urge the first layer 13and second layer 15 apart, including under the weight of the recliningperson, to permit air flow passageways 22 between the two layers, andthus between the surface, F, of the viscoelastic foam mattress and thesurface, S, of a reclining person's skin. Air circulating through theseair flow passageways 22 assists in cooling, and in removal ofperspiration or other moisture, by evaporation.

In the implementations shown in FIGS. 2, 3 and 5, the fabric may be atwo-layer laminate, with the smooth, technical face surface of therespective fabric layers being adhered together face-to-face and therespective outer, technical back surfaces (carrying the raised surfacesof FIG. 2, the regions of high pile and low pile of FIG. 3, or the pilepillars of FIG. 5) facing outward at both surfaces. For example,referring to FIG. 7, laminate 300 includes two fabrics 302, 304, thesmooth surfaces of which are adhered together at an interface 306. Eachfabric carries a raised pile area 308, 310 on its technical back surface312, 314.

The fabrics discussed above with reference to FIGS. 3-6 will now bediscussed in further detail.

Fabrics Having a Pattern of High and Low/No Pile Regions

In the engineered knit fabrics 211′ discussed above with reference toFIGS. 3 and 8, the various regions can have pile of predetermined fiberdensity and predetermined pile height. The contrast of cushioning andairflow may be achieved, for example, by forming regions of differentpile heights (e.g., using different sinker heights), different piledensities (e.g., using full face velour and velour with pattern of pileand no pile), and/or different types of yarns (e.g., using flat yarnswith low shrinkage and texture yarns with high shrinkage). Regions ofselected shape and size can be arranged in predetermined desiredpattern, tailored, as discussed above, for use by persons of differentages and different genders, etc. and for other factors, such asseasonality, etc.

The surfaces of regions of relatively high pile height may be, forexample, plain velour. Typically, the yarn and the pile density ismaintained constant for all regions, again for simplicity ofmanufacture. The three dimensional pattern may exist on one or bothsides of the fabric. For example, if the fabric is formed by a reverseplaiting process, the three dimensional pattern will exist on both sidesof the fabric, typically, in register.

The engineered thermal fabric articles can be produced by any proceduresuitable for creating regions of contrasting pile heights and/or regionswith no pile, in predetermined designs. Examples of suitable proceduresinclude electronic needle and/or sinker selection; tubular circular orterry loop knit construction, e.g. by reverse plaiting, to form doubleface fleece or to form pseudo single face fabric, or by regularplaiting, to form single face fleece; warp knit construction; wovenconstruction; and fully fashion knit construction.

To simplify manufacturing, in some implementations, e.g., as shown inFIG. 4 and discussed above, the regions of contrasting performance arearranged in band form, extending across the mattress cover.

Any suitable yarn or fibers may be employed in forming the engineeredthermal fabrics. Examples of suitable yarn or fibers include syntheticyarn or fibers formed, e.g., of polyester, nylon or acrylic; naturalyarn or fibers formed, e.g., of cotton or wool; regenerate yarn orfibers, such as rayon; and specialty yarn or fibers, such as aramid yarnor fibers, as sold by E.I. duPont de Nemours and Company, Inc. under thetrademarks NOMEX® and KEVLAR®.

Fabrics Having Pile Pillars

Referring to FIGS. 5 and 14, the raised surface fabric 111 discussedabove includes a plurality of courses of loop yarn 113 integrated withstitch or backing yarn 115. The manner in which pile pillars are formedin this fabric will be discussed in detail below.

First, loop yarn 113 is plaited around stitch yarn 115 in order todefine a plurality of fabric loops 114 (FIG. 15). Fabric 111 has acircular knit reverse plaited construction suitable for generating atwo-face-surface fabric, as described below.

Once fabric 111 is formed, technical face 117 is napped or otherwiseraised (FIG. 16). The napping process is carried out in a manner tomaintain full loop coverage with minimal distortion of technical back119. In particular, during the napping process, the integrity of loopyarn 113 on technical back 119 may, to some extent, be compromised, asit is pulled shorter, due to the napping process. Accordingly, loop yarn113 generally must be knit longer, e.g. utilizing sinker loops of atleast 2.0 mm or greater, in order to be able to shear loops 114 alongtechnical back 119 at the conclusion of the napping process.

Once the napping or raising process is completed, loops 114 alongtechnical back 119 are sheared, as shown in FIG. 17. Generally, theshearing step takes place after the napping step. If shearing takesplace as the first fabric finishing step, as is usual for standardsingle face cut loop fabrics, the cut loops 114 can be pulled throughthe back to the face during any subsequent napping process.

The channels between pile pillars may be formed using, for example, thetechniques described in U.S. Pat. No. 6,927,182, the complete disclosureof which is incorporated herein by reference. In such techniques,vertical channels are constructed with the use of tipped and tiplesssinkers, high and low sinkers, or some combination of both (e.g., 4tipped sinkers, 2 tipless, 3 tipped sinkers, 2 tipless, repeat; 3 highsinkers, 1 low sinker, 2 high sinkers, 2 low sinkers, repeat; etc.).Horizontal channels may be created by removing the loop yarn from one ormore feeds in some arrangement, or with the use of a shrinkable loopyarn which creates a channel after processing with wet (e.g., hot water,steam) or dry (air) heat (e.g., 4 loop in, 2 loop out, 3 loop in, 2 loopout, repeat; 3 low shrinkage loop, 3 high shrinkage loop, 3 lowshrinkage loop, 3 high shrinkage loop, repeat; etc.).

Loop yarn 113 generally has bulk greater than that of the stitch yarn115. For example, loop yarn 113 may have a denier of between about 70and 600, while stitch yarn 115 has a denier of between about 30 and 150.Loop yarn 113 is preferably formed of 100% polyester or nylon. Loop yarn113 may also be formed of other materials such as acrylic. Stitch yarn115 may be formed, e.g., of polyester or nylon.

The fabric 111 may be knit on a standard terry sinker loop knittingmachine or on a jacquard machine, the latter enabling the production ofdifferent height fabric loops along the technical back of the fabric.

Two-Layer Fabrics

The two-layer fabrics 11 described above with reference to FIGS. 6 and10 may be prepared by knitting a three-dimensional knit fabric on adouble-needle bar warp knitting machine or circular knitting machine,both of which are well known in the art. As shown in FIGS. 11 and 12,the three-dimensional knit spacer fabric is generally indicated at 11and includes a first fabric layer 13 formed of stitch yarn 17, a secondfabric layer 15 formed of stitch yarn 19, and pile yarn 21interconnecting the two layers. In addition, knit fabric 11 includesbacking or lay-in yarns 25 and 26 (FIG. 11), held by stitch yarns 17 and19 respectively.

Pile yarns 21 have sufficient resilience and stiffness to space the twofabric layers apart, e.g., including when pressure is applied upon afabric layer outer surface. The pile yarns 21 extend generally betweenthe first fabric layer 13 and the second fabric layer 15 and through theair flow region therebetween. As discussed above, the resilientseparation provided by pile yarns 21 enhances circulation of air betweenthe reclining surface of viscoelastic foam and an opposed skin surfaceof the person reclining upon the cover. The pile yarns are spaced andpositioned to resiliently urge apart the two fabric layers, therebymaintaining the air flow region to optimize user comfort. Moreover, thepile yarns 21 are sufficiently spaced from one another to allowcirculating air flow through the intermediate region of the fabric 11.This enhanced air flow helps to prevent bed sores, which can occur dueto constant body pressure and limited air circulation.

Pile yarn 21 may be knit with between 16 and 28 wales per inch and 14 to36 courses per inch. This density enhances the ability of the fabric tomaintain the spacing of the two layers under pressure. Pile yarn 21 maybe made of the same material as the two fabric layers, or may be made ofa different material. In order to render the interconnecting pile yarnresilient, the yarn may be made of a resilient material such asmonofilament or multifilament polyester, nylon, etc. Pile yarn 21 mayhave a fineness of between 40 and 600 denier, e.g., between 40 and 300denier, with an individual fiber fineness of 1 to 12 dpf.

The pile yarn may be made from fibers that have been renderedhydrophilic in order to facilitate the transport of moisture from toplayer 13 to layer 15. Stitch yarn 17 of top layer 13 is also preferablymade of fibers that have been rendered hydrophilic. This constructionfacilitates moisture transport away from the body, maintaining acomfortable top layer and air circulation next to the skin. The toplayer 13 may be chemically treated or it may be formed of modifiedfibers that render the fabric layer hydrophilic, as described in U.S.Pat. No. 5,312,667, the complete disclosure of which is incorporatedherein by reference. The transport of water from the surface issubstantially enhanced by the hydrophilic nature of the top layerbecause liquid moisture is readily transportable along the surface ofthe yarn fibers of the layer.

Top layer 13 may be formed of stitch yarn having a fineness of between50 and 600 denier with an individual fiber fineness in the range ofbetween 0.3 and 2.5 dpf, if multifilament. Backing or lay-in yarns 25and 26 of top layer 13 may be multifilament and may have a fineness ofbetween 70 and 300 denier, with an individual fiber fineness of 0.5 to5.0 dpf.

The stitch yarns may be formed of synthetic material such as polyester,acrylic or nylon, or in some cases a natural material such as cotton.The yarns may be filament or spun, textured or fully oriented.Preferably, stitch yarns 17 and 19 and backing yarns 25 and 26 areformed of polyester or nylon that has been rendered hydrophilic in orderto enhance transport of perspiration or water.

Second fabric layer 15 may be the same as top layer 13 or may havedifferent characteristics. Layer 15 may in some cases consist ofhygroscopic fibers in order to absorb and hold a considerable volume ofmoisture. Particularly, backing yarn 26 of second fabric layer 15 may beformed of moisture absorbent material such as cotton (which absorbs 2 to3 times its weight of water), rayon, wool or a super absorbent fibersuch as a hydrolyzed copolymer of acrylic acid (which absorbs betweentwo and eight times its weight). In accordance with the disclosure, anysuitable moisture absorbent material may be used, e.g., natural fibersor synthetics, so long as the yarn or fiber material chosen for layer 15has relatively greater moisture absorbency than the fiber or yarn oflayer 13.

The use of a super absorbent fiber is quite desirable in that the fiberswill absorb many times their own weight, even when under pressure, andwill retain the absorbed liquid when subjected to pressure. Examples ofsuitable types of super absorbent fibers are described in U.S. Pat. No.5,344,698, the complete disclosure of which is incorporated herein byreference.

If cotton or rayon fibers are used for the second fabric layer, they maybe chemically modified after knitting the composite fabric by treatmentwith alkyl chlorides and cross-linking of the resultant ethers to formcarboxymethylated cellulosic fibers, as known to one of skill in theart, in order to render the second layer super absorbent.

The surface of top fabric layer 13 may be sanded, brushed or napped,forming a pile or velour surface. The yarn which is more coarse, i.e.either the stitch yarn or the interconnecting pile yarn, is napped.Generally the yarn napped is a multifilament yarn.

Optionally, as discussed above, the fabric may incorporate elastomericyarn, such as LYCRA or SPANDEX, in one or both of lay-in yarns 25 and 26of layers 13 and 15, respectively, and/or the stitch yarns 17, 19. Suchyarn will have a total fineness between about 70 and 300 denier. Thiswill enhance softness and flexibility of the layer, and thus itsconformability to the viscoelastic foam. The elastomeric yarn may alsobe added to the stitch yarn of one or both layers.

Top layer 13 may be coated with a breathable barrier layer, i.e., abarrier layer that is impermeable to liquid water but permeable to watervapor. The barrier layer deposited on the fabric layer is preferably afilm with good moisture vapor transmission characteristics. Suitablefilms include polyurethane, polysiloxane and polysulfane.

The barrier layer may be applied to the fabric layer by methods wellknown in the art. These include transfer coating, in which the barrierlayer is first placed or laid on a carrier. Thereafter, the film isplaced on the fabric layer, and the carrier is then discarded.Alternative methods for applying the film include direct lamination ofan extruded film, as well as direct roller coating of a solution ontothe fabric layers from which the solvent is then evaporated. A furthermethod for applying the barrier layer is first applying an adhesive onthe fabric layer by spraying or gravure printing and then placing aself-supporting film on top of the adhesive in the manner of lamination.

A portion of the pile yarns 21 interconnecting the two layers may beperpendicular to each of the first and second fabric layers, while theremaining pile yarns 21 are disposed at varying angles between the twolayers, with the result that the former will be of lesser and the latterof greater bulk. Such constructions are described in U.S. Pat. No.6,156,406, the complete disclosure of which is incorporated herein byreference.

A number of implementations have been described. Nevertheless, it willbe understood that various modifications may be made without departingfrom the spirit and scope of this disclosure. Accordingly, otherimplementations are within the scope of the following claims.

1. A cover for a mattress having a reclining surface of viscoelasticfoam, the cover comprising: a circular knit fabric body having four-waystretch and defining: a first pile surface disposed in engagement withthe reclining surface; an opposite, second pile surface disposed forengagement by a person reclining upon the cover with the first surfacedisposed in engagement with the reclining surface; and at least one airflow region for enhanced circulation of air between the recliningsurface of viscoelastic foam and an opposed skin surface of the personreclining upon the cover.
 2. The cover for a mattress having a recliningsurface of viscoelastic foam of claim 1, wherein at least one of saidfirst pile surface and said second pile surface defines one or moreregions with relatively high pile disposed among one or more regions ofrelatively low pile or no pile, with the one or more regions ofrelatively low pile or no pile defining the at least one air flow regionfor enhanced circulation of air between the reclining surface ofviscoelastic foam and an opposed skin surface of the person recliningupon the cover.
 3. The cover for a mattress having a reclining surfaceof viscoelastic foam of claim 2, wherein the one or more regions withrelatively high pile and the one or more regions of relatively low pileor no pile are arranged upon at least one of said first pile surface andsaid second pile surface by engineered body mapping techniques in amanner to position the at least one air flow region for enhancedcirculation of air between the reclining surface of viscoelastic foamand an opposed skin surface of the person reclining upon the cover inaccordance with requirements of corresponding body regions of the personreclining upon the cover.
 4. The cover for a mattress having a recliningsurface of viscoelastic foam of claim 2, wherein the one or more regionswith relatively high pile and the one or more regions of relatively lowpile or no pile are arranged upon at least one of said first pilesurface and said second pile surface by standard knitting designtechniques in a manner to position the at least one air flow region forenhanced circulation of air generally between the reclining surface ofviscoelastic foam and an opposed skin surface of the person recliningupon the cover in a regular pattern.
 5. The cover for a mattress havinga reclining surface of viscoelastic foam of claim 3 or claim 4, whereincontrasting height among regions of relatively high pile and regions ofrelatively low pile or no pile is established by contrasting height ofsinker loops.
 6. The cover for a mattress having a reclining surface ofviscoelastic foam of claim 5, wherein said circular knit fabric bodycomprises stitch yarn with spandex.
 7. The cover for a mattress having areclining surface of viscoelastic foam of claim 5, wherein said circularknit fabric body comprises stretch stitch yarn.
 8. The cover for amattress having a reclining surface of viscoelastic foam of claim 5,wherein said sinker loops of said at least one of said first pilesurface and said second pile surface are in unnapped yarn form.
 9. Thecover for a mattress having a reclining surface of viscoelastic foam ofclaim 5, wherein said sinker loops of said at least one of said firstpile surface and said second pile surface are in napped, velour form.10. The cover for a mattress having a reclining surface of viscoelasticfoam of claim 5, wherein said sinker loops of said at least one of saidfirst pile surface and said second pile surface are in cut loop formwithout pre-napping.
 11. The cover for a mattress having a recliningsurface of viscoelastic foam of claim 5, wherein the circular knitfabric body comprises hydrophilic fibers.
 12. The cover for a mattresshaving a reclining surface of viscoelastic foam of claim 5, wherein thecircular knit fabric body comprises material selected from the groupconsisting of cotton and wool.
 13. The cover for a mattress having areclining surface of viscoelastic foam of claim 5, wherein the circularknit fabric body comprises fibers of synthetic material.
 14. The coverfor a mattress having a reclining surface of viscoelastic foam of claim13, wherein the synthetic material is selected from the group consistingof polyester; nylon; acrylic; polyester, nylon or acrylic that has beenrendered hydrophilic; and blends thereof.
 15. The cover for a mattresshaving a reclining surface of viscoelastic foam of claim 1 or claim 2,wherein the circular knit fabric body has chemical treatment for one ormore properties selected from the group consisting of wickingenhancement, stain release, water repellency, stain repellency,antimicrobial properties, and oil repellency.
 16. The cover for amattress having a reclining surface of viscoelastic foam of claim 15,wherein said fabric body comprises hydrophilic fibers.
 17. The cover fora mattress having a reclining surface of viscoelastic foam of claim 1 orclaim 2, wherein said fabric body comprises a fabric laminate.
 18. Thecover for a mattress having a reclining surface of viscoelastic foam ofclaim 2, wherein said one or more regions of relatively high pilecomprises a plurality of spaced-apart pile pillars and said one or moreregions of relatively low pile or no pile comprises intersectingchannels extending among said pile pillars and defining said at leastone air flow region for enhanced circulation of air between thereclining surface of viscoelastic foam and an opposed skin surface ofthe person reclining upon the cover.
 19. The cover for a mattress havinga reclining surface of viscoelastic foam of claim 18, wherein saidfabric body comprises a double bar raschel warp knit construction. 20.The cover for a mattress having a reclining surface of viscoelastic foamof claim 18, wherein said fabric body comprises a knit with about 16 toabout 28 wales per inch.
 21. The cover for a mattress having a recliningsurface of viscoelastic foam of claim 18, wherein said fabric bodycomprises a knit structure with about 14 courses to about 36 courses perinch.
 22. The cover for a mattress having a reclining surface ofviscoelastic foam of claim 18, wherein yarns of said fabric body havefineness in a range of about 40 to about 600 denier.
 23. The cover for amattress having a reclining surface of viscoelastic foam of claim 18,wherein yarns of said fabric body comprise individual fibers havingfineness in a range of about 1 dpf to about 12 dpf.
 24. A cover for amattress having a reclining surface of viscoelastic foam, said covercomprising: a fabric body defining: a first surface disposed inengagement with the reclining surface; an opposite, second surfacedisposed for engagement by a person reclining upon the cover; and atleast one air flow region for enhanced circulation of air between thereclining surface of viscoelastic foam and an opposed skin surface ofthe person reclining upon the cover.
 25. The cover for a mattress havinga reclining surface of viscoelastic foam of claim 24, wherein saidfabric body comprises a first fabric layer defining said first surfaceand a second fabric layer defining said opposite, second surface, withsaid at least one air flow region defined therebetween; and said fabricbody further comprises a plurality of intermediate members extendinggenerally between the first fabric layer and the second fabric layer andthrough said at least one air flow region for enhanced circulation ofair between the reclining surface of viscoelastic foam and an opposedskin surface of the person reclining upon the cover.
 26. The cover for amattress having a reclining surface of viscoelastic foam of claim 25,wherein said plurality of intermediate members are disposed toresiliently urge apart said first fabric layer and said second fabriclayer.
 27. The cover for a mattress having a reclining surface ofviscoelastic foam of claim 25, wherein the first fabric layer ispermeable to water vapor and impermeable to liquid water.
 28. The coverfor a mattress having a reclining surface of viscoelastic foam of claim25, wherein each of the first fabric layer and the second fabric layercomprises stitch yarn.
 29. The cover for a mattress having a recliningsurface of viscoelastic foam of claim 28, wherein the stitch yarn of thefirst fabric layer has fineness in a range of about 50 to about 600denier
 30. The cover for a mattress having a reclining surface ofviscoelastic foam of claim 28, wherein the stitch yarn of the firstfabric layer has individual fiber fineness in the range of about 0.3 toabout 6.0 dpf.
 31. The cover for a mattress having a reclining surfaceof viscoelastic foam of claim 28, wherein the stitch yarn of the firstfabric layer comprises hydrophilic fibers.
 32. The cover for a mattresshaving a reclining surface of viscoelastic foam of claim 28, wherein thestitch yarn of the first fabric layer comprises fibers of syntheticmaterial.
 33. The cover for a mattress having a reclining surface ofviscoelastic foam of claim 32, wherein the synthetic material isselected from the group consisting of polyester; acrylic; nylon;polyester, acrylic or nylon that has been rendered hydrophilic; andblends thereof.
 34. The cover for a mattress having a reclining surfaceof viscoelastic foam of claim 28, wherein the stitch yarn of the secondfabric layer comprises natural fibers.
 35. The cover for a mattresshaving a reclining surface of viscoelastic foam of claim 34, wherein thestitch yarn of the second fabric layer comprises material selected fromthe group consisting of cotton and wool.
 36. The cover for a mattresshaving a reclining surface of viscoelastic foam of claim 28, wherein thesecond fabric layer further comprises lay-in yarn held by the stitchyarn.
 37. The cover for a mattress having a reclining surface ofviscoelastic foam of claim 36, wherein the lay-in yarn comprises anelastomeric yarn.
 38. The cover for a mattress having a recliningsurface of viscoelastic foam of claim 37, wherein the lay-in yarncomprises total fineness in a range of about 70 to about 300 denier. 39.A method of forming a cover for a mattress having a reclining surface ofviscoelastic foam, the cover, said method comprising the steps of:forming a circular knit fabric having four way stretch, with a firstpile surface and an opposite, second pile surface and defining at leastone air flow region for enhanced circulation of air between thereclining surface of viscoelastic foam and an opposed skin surface ofthe person reclining upon the cover; and forming the circular knitfabric into a cover for a mattress having a reclining surface ofviscoelastic foam.